The present invention relates to an item handling system, in particular an item handling system for providing an indication of the readability of machine-readable symbols printed by an item preparation station, thereby enabling control of the quality of printed symbols. The present invention finds particular application as a mail handling system in handling mail items.
Mail items for which postal charges are metered by postage metering apparatus receive an imprint of a postage indicium from the postage metering apparatus to evidence that accounting has been effected in respect of the postal charge for the mail item.
Traditionally, postage metering apparatus have been arranged to print a relatively simple form of indicium comprising a graphic design and items of postal information. The postal information usually comprises an identification of the postage metering apparatus, an identification of the postal depot receiving the mail items from the mailer, the postal charge and the date of mailing. This relatively simple form of postage indicium enables a human visual check of mail items to determine that postal charges have been accounted for by the postage metering apparatus. As these printed postage indicia are only subject to a visual check, the quality of the imprint has not to date been critical, provided that the quality of the imprint is sufficient to enable the personnel at the postal depot to determine that an imprint had been applied and read the amount of the postal charge to determine that the correct postal charge for the mail item has been applied.
With the advent of the use of digital printing techniques for printing postage indicia, and a desire to provide security against fraudulent printing of postage indicia, it is now proposed to include additional information in the postage indicia. This additional information includes cryptographic information that can be used to verify the authenticity of the printed postage indicia and enable the automation of the reading of the information in the indicia and the verification of the indicia. Accordingly, it is necessary that the quality of the imprint of the postage indicia be maintained at a sufficient level as to ensure successful machine reading of the information in the postage indicia. Mail handling authorities and operators are seeking to achieve 100% readability of postage indicia printed on mail items. However, imperfections can occur in the imprint of the postage indicia which result in the machine-reading equipment being incapable of unambiguously reading the information in the printed postage indicia on every mail item, and, moreover, these imperfections which affect the machine readability of printed postage indicia often/ would not be evident from a human visual inspection.
Various factors can affect the quality of the imprints of postage indicia, and hence the machine readability of printed postage indicia. One factor is a restricted supply of the ink used to form imprints on mail items, for example, owing to a low level of ink in an ink supply to the printer. For example, where an ink-jet printer is used in a postage metering apparatus to print the postage indicia, after substantial use of an ink-jet print cartridge, the ink supply to the ink-jet nozzles may be so depleted as to result in poor quality printing of the indicia or the ink-jet nozzles may become partially or totally blocked such that dots required to print the postage indicia are only partially formed or are wholly absent. Another factor is the improper installation of print cartridges in postage metering apparatus. With ink-jet print cartridges, this results in poor electrical connections to the print cartridges or even lack of connection to some of the electrical terminals of the print cartridges. As a result, ones of the ink-jet nozzles may not be operative. Improper installation of print cartridges can also result in misalignment of the ink-jet nozzles such that printed dots forming the postage indicia imprint are misaligned and the postage indicia imprint is distorted. Another factor is the kind of material of the mail items. The quality of the imprint is dependent upon the use of mail items, for example envelopes, formed of a material which is suited to the particular technique used in printing the postage indicia.
Whilst all of these factors are under the control of a human operator and corrective action could be taken by the operator, the printing of machine-readable symbols in printed indicia which are of a quality which is significantly lower than that desired may not be evident to the human operator from a visual inspection. Thus, a human operator would probably not be able to determine that the quality of an imprint is lower than that desired for machine readability, particularly where the quality is only marginally lower than that desired.
It is thus an aim of the present invention to provide an item handling system, an item preparation station and an item handling station which provide an indication as to the readability of printed machine-readable symbols, thereby enabling control of the quality of printed symbols.